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Diff Checker

Compare two texts or code files side by side and highlight differences. Find added, removed, and changed lines instantly with colour-coded diff output.

Used 12.2K times today

How to Use Diff Checker

  1. 1

    Paste original text

    Enter your original or baseline text in the left panel.

  2. 2

    Paste modified text

    Enter the updated or modified version in the right panel.

  3. 3

    Review the diff

    Added lines are highlighted in green, removed lines in red, and unchanged lines are shown in grey. Inline character-level diffs are also shown.

Frequently Asked Questions

Does it work for code in any language?
Yes. The diff checker is language-agnostic and works with plain text, JSON, JavaScript, Python, SQL, HTML, CSS, Markdown, or any other text-based format.
Can I compare more than two files?
The current tool supports two-way comparison (original vs. modified). For three-way merge comparisons, a Git client or dedicated merge tool is recommended.
What diff algorithm is used?
The tool uses the Myers diff algorithm, which is the same algorithm used by Git. It produces the minimal edit distance diff between two texts.

About Diff Checker

The Diff Checker provides a clear, colour-coded side-by-side comparison of two pieces of text or code. Identifying what changed between two versions of a config file, API response, or code snippet is a frequent debugging and review task, and a visual diff makes it immediately obvious without manual scanning.

The diff engine highlights changes at both the line level and the character level within changed lines, making it easy to spot a single changed character in a long string — critical when debugging JSON keys, regex patterns, or configuration values. All comparison happens locally in the browser with no server transmission.

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